Antibody ailing gut badly needs initially (10)

I believe the answer is:

agglutinin

'antibody' is the definition.
(agglutinin is a kind of antibody)

'ailing gut badly needs initially' is the wordplay.
'badly' indicates anagramming the letters.
'initially' suggests taking the first letters.
The first letter of 'needs' is 'n'.
'ailing'+'gut'='ailinggut'
'ailinggut' with letters rearranged gives 'agglutini'.
'agglutini'+'n'='AGGLUTININ'

(Another definition for agglutinin that I've seen is " Antibody causing adhesion".)

I've seen this clue in The Times.

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